[BNX2]: Fix bug in irq handler and add prefetch

Fix bug in bnx2_interrupt() that caused an unnecessary register read.
The BNX2_PCICFG_MISC_STATUS should only be read when the status tag
has not changed.

Add prefetch of the status block in bnx2_msi() similar to tg3_msi().
The status block is not touched in bnx2_msi() and prefetching it will
speed up bnx2_poll() that will run on the same CPU that received the
MSI.

Update version.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>